Download Ch 9 Cell Respiration HW Packet

9.1 Cellular Respiration: An Overview
Name:
Biology
Date:
Period:
Lesson Objectives
 Explain where organisms get the energy they need for life processes.
 Define cellular respiration.
 Compare photosynthesis and cellular respiration.
Chemical Energy and Food - Chemical energy is stored in food molecules.
 Energy is released when chemical bonds in food molecules are broken.
 Energy is measured in a unit called a calorie, the amount of energy needed to raise the temperature of 1 gram of
water 1Celsius.
 Fats store more energy per gram than do carbohydrates and proteins.
Overview of Cellular Respiration - Cellular respiration is the process that releases energy from food in the presence of
oxygen.
Cellular respiration captures the energy from food in three main stages:
 glycolysis
 the Krebs cycle
 the electron transport chain
Glycolysis does not require oxygen. The Krebs cycle and electron transport chain both require oxygen.
 Aerobic pathways are processes that require oxygen.
 Anaerobic pathways are processes that occur without oxygen.
Comparing Photosynthesis and Cellular Respiration The energy in photosynthesis and cellular respiration flows in
opposite directions. Their equations are the reverse of each other.
 Photosynthesis removes carbon dioxide from the atmosphere, and cellular respiration puts it back.
 Photosynthesis releases oxygen into the atmosphere, and cellular respiration uses oxygen to release energy from
food.
Chemical Energy and Food
For Questions 1–4, complete each statement by writing the correct word or words.
1. A calorie is a unit of
.
2. The Calorie used on food labels is equal to
3. A Calorie is also referred to as a
calories.
.
4. Cells use the energy stored in chemical bonds of foods to produce compounds that directly power the cell’s
activities, such as
.
Overview of Cellular Respiration
For Questions 5–10, complete each statement by writing the correct word or words.
5. The equation that summarizes cellular respiration, using chemical formulas, is
6. If cellular respiration took place in just one step, most of the
light and
.
would be lost in the form of
7. Cellular respiration begins with a pathway called
__________________ of the cell.
, which takes place in
8. At the end of glycolysis, about
__________________ molecule.
percent of the chemical energy is locked in the bonds of the
1
9. Cellular respiration continues in the
electron transport chain.
of the cell with the
10. The pathways of cellular respiration that require oxygen are said to be
that do not require oxygen are said to be
.
and
. Pathways
Complete the illustration by adding labels for the three main stages of cellular respiration.
Comparing Photosynthesis and Cellular Respiration
For Questions 11-14, write True if the statement is true. If the statement is false, change the underlined word or
words to make the statement true.
11. The energy flow in photosynthesis and cellular respiration occurs in the same direction.
12. Photosynthesis deposits energy in Earth’s “savings account” for living organisms.
13. Cellular respiration removes carbon dioxide from the air.
14. Photosynthesis takes place in nearly all life.
Complete the table comparing photosynthesis and cellular respiration.
A Comparison of Photosynthesis and Cellular Respiration
Photosynthesis
Cellular Respiration
Aspect
Function
Location of
reactions
Reactants
Products
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9.2 The Process of Cellular Respiration
Name:
Biology
Date:
Period:
Lesson Objectives
 Describe what happens during glycolysis.
 Describe what happens during the Krebs cycle.
 Explain how high-energy electrons are used by the electron transport chain.
 Identify how much ATP cellular respiration generates.
Glycolysis - The word glycolysis literally means “sugar-breaking.” The end result is 2 molecules of a 3-carbon molecule called
pyruvic acid.
 2 ATP molecules are used at the start of glycolysis to get the process started.
 High-energy electrons are passed to the electron carrier NAD+, forming two molecules of NADH.
 4 ATP are synthesized during glycolysis for a net gain of 2 ATP.
The Krebs Cycle The second stage of cellular respiration is the Krebs cycle, which operates only when oxygen is available. The
Krebs cycle is a series of energy-extracting reactions.
 Pyruvic acid produced by glycolysis enters mitochondria. In the innermost compartment of a mitochondrion, or the matrix,
pyruvic acid molecules are broken down into carbon dioxide and acetyl-CoA molecules.
 Acetyl-CoA combines with a 4-carbon compound, producing a 6-carbon molecule—citric acid. Energy released by the
breaking and rearranging of carbon bonds is captured in ATP, NADH, and FADH 2.
 The Krebs cycle produces four types of products:
1. high-energy electron carriers (NADH and FADH2)
2. carbon dioxide
3. 2 ATP molecules (per glucose molecule)
4. the 4-carbon molecule needed to start the cycle again
Electron Transport and ATP Synthesis The electron transport chain uses the high-energy electrons from glycolysis and the Krebs
cycle to convert ADP into ATP.
 The electron carriers produced during glycolysis and the Krebs cycle bring high-energy electrons to the electron transport
chain. Oxygen is the final electron acceptor.
 The passing of electrons through the electron transport chain causes H + ions to build up in the intermembrane space, making
it positively charged relative to the matrix.

+
The charge difference across the membrane forces H ions through channels in enzymes known as ATP synthases. As the
ATP synthases spin, a phosphate group is added to ADP, generating ATP.
The Totals Together, glycolysis, the Krebs cycle, and the electron transport chain generate about 36 molecules of ATP
per molecule of glucose.
Glycolysis - Complete the diagram by writing on the lines
provided the names and numbers of molecules used and
produced during glycolysis.
3
Steps of Cellular Respiration
Glycolysis
Krebs cycle
Electron transport chain
Where in cell it
occurs
Starting reactants
Ending products
Number of ATP
molecules either
produced or gained
Is oxygen required?
1. Why is it an investment for the cell to use two ATP at the beginning of glycolysis?
2. What are two advantages of glycolysis?
The Krebs Cycle
For Questions 3-6, write True if the statement is true. If the statement is false, change the underlined word
or words to make the statement true.
3. The pyruvic acid produced in glycolysis enters the chloroplasts if oxygen is present
in a cell.
4. In the matrix, pyruvic acid is converted to lactic acid before the Krebs cycle begins.
5. The compound that joins with a 4-carbon molecule in the Krebs cycle is called
acetyl-CoA.
6. Carbon dioxide is the only product of the Krebs cycle that is not re-used or used in
other stages of cellular respiration.
4
Electron Transport and ATP Synthesis - The electron transport chain uses the high-energy electrons
produced by the Krebs cycle to move hydrogen ions from one side of the inner membrane to the other.
Complete the flowchart about electron transport. Use the terms in the box.
intermembrane
positively
electron transport chain
inner membrane
ATP synthase
ATP
High-energy electrons from NADH and FADH2 are passed into and along the
.
The energy from the electrons moving down the chain is used to move H+ ions across the
.
H+ ions build up in the
the matrix negatively charged.
space, making it
H+ ions move through channels of
charged and making
in the inner membrane.
The ATP synthase uses the energy from the moving ions to combine ADP and a phosphate, forming highenergy
.
For Questions 7-12, complete each statement by writing the correct word or words.
7. In eukaryotes, the electron transport chain is composed of a series of electron carriers located in the
_____________________________of the mitochondrion.
8. In prokaryotes, the electron transport chain is in the _________________________________.
9. __________________ serves as the final electron acceptor of the electron transport chain.
10. _______________ and _______________ pass high-energy electrons to the electron transport chain.
11. The transfer of high-energy electrons down the electron transport chain causes
____________ to be transported across the mitochondrial membrane.
12. ATP synthases produce the force needed to add one
to each ADP
molecule by spinning when hydrogen ions flow through them.
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The Totals
13. What happens to the carbon dioxide that results from the Krebs cycle?
14. How many ATP molecules per glucose molecule does a cell gain from each of the three stages of cellular
respiration?
15. Besides glucose, what other kinds of molecules can be used to produce ATP in cellular respiration?
16. Why is cellular respiration considered an efficient process?
17. Where does the heat that warms your body come from? Explain your answer.
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9.3 Fermentation
Name:
Biology
Date:
Period:
Lesson Objectives
 Explain how organisms get energy in the absence of oxygen.
 Identify the pathways the body uses to release energy during exercise.
Fermentation - releases energy from food molecules by producing ATP without oxygen. Cells convert NADH to the
electron carrier NAD+. This allows glycolysis to produce a steady stream of ATP. There are two forms of fermentation.
Both start with the reactants pyruvic acid and NADH.
 alcoholic fermentation produces ethyl alcohol and carbon dioxide
o occurs in yeast and a few other microorganisms
o produces alcoholic beverages and causes bread dough to rise
 lactic acid fermentation produces lactic acid
o occurs in most organisms, including humans
o used to produce beverages such as buttermilk and foods such as cheese, yogurt, and pickles
Energy and Exercise - The body uses different pathways to release energy.
 For short, quick bursts of energy, the body uses ATP already in muscles as well as ATP made by lactic acid
fermentation.
 For exercise longer than about 90 seconds, cellular respiration is the only way to continue generating a supply of
ATP.
Fermentation
For Questions 1–6, write True if the statement is true. If the statement is false, change the underlined word or
words to make the statement true.
1. Glycolysis provides the pyruvic acid molecules used in fermentation.
2. Fermentation allows glycolysis to continue by providing the NADPH needed to
accept high-energy electrons.
3. Fermentation is an aerobic process.
4. Fermentation occurs in the mitochondria of cells.
5. Alcoholic fermentation gives off carbon dioxide and is used in making bread.
6. Most organisms perform fermentation using a chemical reaction that converts
pyruvic acid to lactic acid.
Compare and contrast fermentation and cellular respiration table.
Aspect
Fermentation
Cellular Respiration
Function
Reactants
Products
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Compare and contrast alcoholic fermentation and lactic acid fermentation.
Lactic Acid Fermentation
Alcoholic Fermentation
Reactants
End products
Uses by humans
Label the process that shows alcoholic fermentation. Label the process that shows lactic acid fermentation.
Glycolysis
Glucose
CYTOPLASM
NAD+
cycles
back
NAD+
cycles
back
2 Pyruvic Acid
2 CO2
2 Ethyl Alcohol
2 Lactic Acid
Circle the correct answer. Questions may have more than one correct answer.
7. Alcoholic fermentation is used to make which product?
bread
cheese
yogurt
pickles
8. What kind of taste do lactic acid bacteria give foods?
sweet
salty
sour
spicy
9. What are some milk products made from lactic acid fermentation?
milk
sour cream
yogurt
cheese
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Energy and Exercise
10. What causes humans to become lactic acid fermenters?
11. What are three main sources of ATP available for human muscle cells?
12. During a race, how do your muscle cells produce ATP after the store of ATP in muscles is used?
13. Why does a sprinter have an oxygen debt to repay after the race is over?
14. A runner needs more energy for a longer race. How does the body generate the necessary ATP?
15. Why are aerobic forms of exercise so beneficial for weight control?
16. Compare and contrast the role of fermentation and cellular respiration in the actual production of ATP. In
your response, consider which process produces ATP and which process contributes to its production.
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Compare and contrast Alcoholic and Lactic Acid Fermentation.
For Questions 1–7, match the term with its definition.
Term
Definition
1. anaerobic
A. Innermost compartment of a mitochondrion
2. glycolysis
B. Process that forms either lactic acid or ethyl alcohol when no oxygen is present
3. Krebs cycle
C. Stage of cellular respiration that starts with pyruvic acid and produces CO2.
4. calorie
D. Process in which glucose is broken down into two molecules of pyruvic acid
5. matrix
E. “In air”
6. aerobic
F. “Without air”
7. fermentation
G. Amount of energy needed to raise the temperature of 1 gram of water 1°C
8. Which is the process that releases energy by breaking down food molecules in the presence of oxygen?
A. cellular respiration
C. glycolysis
B. electron transport
D. photosynthesis
9. Which is the electron carrier that accepts electrons during glycolysis?
A. ADP
C. NAD+
B. ATP
D. NADP+
10. When comparing cellular respiration and photosynthesis, these two processes are best described as
A. energy-releasing processes.
C. opposite processes.
B. energy-storing processes.
D. similar processes.
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Cell Respiration Web Activity
Use the website below as an introduction to the 3 steps of
cellular respiration: https://goo.gl/Mq3AC9
To begin select “High” for the oxygen level, because
cellular respiration is an aerobic process meaning that it can
only occur in the presence of oxygen.
The first step of cellular respiration is glycolysis. Click on
the Play button to answer the questions about glycolysis.
You can pause the animation at any time.
Glycolysis:
1. Where does glycolysis take place in the cell?
2. During glycolysis, indicate the quantity of each molecule that is produced for every molecule of glucose:
3. Describe how NAD+ is converted into NADH?
4. During glycolysis does NAD+ become oxidized or reduced? How can you tell?
Krebs Cycle:
5. Where in the cell does the Krebs cycle take place?
6. Explain the function of Coenzyme A in Krebs cycle.
7. During the Krebs Cycle, indicate the
quantity of each molecule that is
produced?
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Electron Transport:
8. Describe the location of the electron transport chain.
9. What 2 molecules supply the electron transport chain with high energy electrons?
10. What happens eat time electrons are passed from protein to protein in the electron transport chain?
11. What happens each time hydrogen ions pass through ATP synthase?
12. Describe how ATP Synthase is able to make ATP?
13. How many molecules of ATP are produced from the energy from a single NADH molecule?
14. How many molecule of ATP are produced from the energy from a single FADH2 molecule?
15. Describe how water molecules are created in the electron transport chain?
16. Once the animation has finished playing, click on the button that says “Cellular Respiration Activity” on the
left side of the screen. Drag the terms on the left side of the screen to the correct location on the diagram.
Once you have finished, label the diagram below.
17. Go back to the home page and click on LOW Oxygen Level. How is this process different from the HIGH
Oxygen Level?
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Photosynthesis and Cellular Respiration Review
Name:
Biology
Date:
Period:
1. Distinguish between autotrophs and heterotrophs and give an example of each.
2. Which type(s) of organisms carry out photosynthesis (autotroph/heterotroph)?
3. Why are most plants green?
4. Name the organelle used in photosynthesis.
5. Name the organelle used in cellular respiration.
6. Write the balanced equation for Photosynthesis:
7. Write the balanced equation for Cellular Respiration:
8. What do the two equations have in common?
9. What are the differences between the two equations?
10. How are the two equations they related?
11. Which type(s) of organisms carry out cellular respiration?
12. Name the energy transfer molecule of the cell.
13. Complete the table.
Photosynthesis
Cellular Respiration
Function
Location
Reactants
Products
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14. What are the three parts of an ATP molecule?
1
2
3
1. _______________________________________
2. _______________________________________
3. _______________________________________
15. Energy is released from ATP when a phosphate group is
16. Plants get the energy they need for photosynthesis by absorbing
.
.
17. What drives photosynthesis?
18. What are the reactants for photosynthesis?
19. What are the products for photosynthesis?
20. What are the reactants for respiration?
21. What are the products for respiration?
22. What happens if the intensity of light that a plant receives is increased?
23. What happens if the amount of carbon dioxide that a plant receives is increased?
24. What happens if the amount of water that a plant receives is increased?
25. What happens if the temperature a plant receives is increased?
26. What is the name of the organelle?
27. Name the structures in the figure:
A.
B.
C.
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15
16
Look at the diagram to answer the questions or complete the tasks.
1. Color all the CO2 molecules blue.
2. Are the CO2 molecules entering or leaving the Krebs cycle?
3. Every time NAD+ enters a reaction, what is it transformed into?
4. Color NAD+ and NADH red.
5. Every time FAD enters a reaction, what is it transformed into?
6. Color FAD and FADH2 orange.
7. What is added to ADP to make ATP?
8. Color ADP and ATP yellow.
9. For every glucose molecule (remember that each glucose molecule is split into 2 molecules of pyruvic acid)
how many of each of the follow molecules are formed?
________ CO2
________ ATP
________ NADH
________ FADH2
Read the passage to answer the following questions:
10. Where does the Krebs cycle take place?
11. What is pyruvate converted into in the first reaction? What molecule is given off during the conversion?
12. List the molecules that are produced for every molecule of acetyl CoA that enters the Krebs cycle.
13. What is the fate of…
a. CO2
b. ATP
c. NADH and FADH2
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Cell Respiration Multiple Choice Reasoning
Name:
Biology 6.0
Date:
Period:
Circle the correct answer and then explain why the other answers are NOT correct.
1. The primary purpose of cellular respiration in living organisms is to
(A) remove excess carbon dioxide from the cells.
(B) create water by combining oxygen and hydrogen ions.
(C) produce biologically useful energy in the form of ATP.
(D) create larger complex molecules such as carbohydrates, proteins, and lipids
2. The reactions in glycolysis occur
(A) on the membranes inside the mitochondria.
(B) in the fluid matrix of the mitochondria.
(C) on the exterior mitochondrial membrane.
(D) in the cytoplasm.
3. The products of glycolysis include two pyruvate molecules and
(A) two molecules of oxygen.
(B) two net molecules of ATP.
(C) one molecule of glucose.
(D) one molecule of NADH and one molecule of FADH2.
4. If oxygen is not present in sufficient quantity, pyruvate molecules are converted into
(A) ethanol or lactic acid.
(B) amino acids or fatty acids.
(C) carbon dioxide and water.
(D) acetyl-CoA and citric acid.
5. Prior to entering the Krebs Cycle, each pyruvate molecule loses electrons, hydrogen ions, and a carbon, forming an
energy-rich molecule of
(A) NAD+.
(B) FADH2.
(C) acetyl-CoA.
(D) carbon dioxide.
6. The NADH and FADH2 that are formed in the Krebs Cycle primarily function to
(A) remove the waste product CO2 from the system.
(B) facilitate the production of water by combining hydrogen ions with oxygen.
(C) catalyze the production of ATP from ADP.
(D) transfer electrons to the electron transport system.
7. The inner folded membrane of the mitochondria serves primarily to
(A) separate the many reactions that occur in the organelle.
(B) provide increased surface area for the molecules and reactions of the electron transport system.
(C) provide a surface for the reaction that unites acetyl with Coenzyme A.
(D) produce enzymes that facilitate the splitting of water for oxygen release.
8. When human muscles are exercised and oxygen is depleted, the muscles can continue to produce energy by
(A) taking oxygen from other cells and continuing aerobic respiration.
(B) breaking down fatty acids.
(C) increasing the speed of the reactions in the Krebs Cycle.
(D) using fermentation reactions to facilitate glycolysis.
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9. After the Krebs Cycle only a small portion of the energy of glucose has been converted to ATP. At this point the
majority of usable energy is contained in
(A) NADH and FADH2
(B) pyruvate
(C) carbon dioxide
(D) citric acid
10. The terminal electron acceptor in mitochondrial respiration is
(A) hydrogen
(B) NADH
(C) oxygen
(D) carbon dioxide
11. Fermentation reactions contribute to the continued production of ATP in the absence of oxygen by
(A) splitting carbon dioxide and releasing additional oxygen.
(B) recycling NADH molecules to NAD+ molecules.
(C) producing enzymes that convert ADP to ATP.
(D) breaking down ethanol or lactic acid to carbon dioxide and water.
12. Which of the following could be found in autotrophic eukaryotic cells?
I. mitochondria
II. chloroplasts
III. nucleus
(A) I only
(B) II only
(C) III only
(D) II and III only
(E) I, II, and III
13. All of the following statements are true with regard to mitochondria and chloroplasts EXCEPT
(A) Both consist of a double phospholipid bilayer.
(B) Both produce ATP.
(C) Both are found in heterotrophs.
(D) Both have internal structures that increase surface area.
14. All of the following provide evidence of an increased rate of cellular respiration EXCEPT
(A) increase in the concentration of CO2.
(B) decrease in the concentration of O2.
(C) increased activity of ATP synthase.
(D) an increase in the concentration of lactic acid.
15. Which of the following represents a plausible pathway of electrons through the process of cellular respiration?
(A) GlucosePyruvateAcetyl-CoAFADH2oxygen
(B) GlucoseNADHelectron transport chainAcetyl-CoAoxygen
(C) GlucosePyruvateelectron transport chainNADHAcetyl-CoA
(D) Glucosecarbon dioxideFADH2electron transport chainAcetyl-CoA
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Group 1
1. Using the diagram above, explain how photosynthesis and cellular respiration are complementary
processes.
2. Looking at the diagram above, explain whether anaerobic respiration is energy absorbing or energy
releasing process.
3. Provide correct terms for A, X and Y and explain why you chose each term.
4. If B were prevented from occurring, what would be the first measureable effect on organisms
performing the above processes?
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Group 2
1. Process A is known as
a. Photosynthesis
b. Fermentation
c. Dehydration synthesis
d. Aerobic respiration
2. Glucose is a product of
a. Process A, only
b. Process B, only
c. Process B and process C
d. Process A and process C
The diagrams below show energy transfer. Complete the chart below by describing energy transformations
involved in each process. Describe how energy transformations involved in photosynthesis are related to energy
transformations involved in cellular respiration.
Light Energy
Process
Chemical Energy
(glucose)
Chemical Energy
(ATP)
Mechanical
Energy
Energy Transformation
Photosynthesis
Cellular
Respiration
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Group 3
1. What are the gas bubbles in the diagram?
2. In the setup shown in the diagram, which color light will cause the plant
to produce the smallest number of gas bubbles?
a. red
b. colorless
c. blue
d. green
3. Explain how the color of light can affect the amount of bubbles
produced.
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
4. If the intensity of light is increased, what happens to the amount of bubbles produced?
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
5. What happens if the light is turned off? Think about both sets of reactions in photosynthesis.
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
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Group 4
1. Which of the following best describes the flow of energy in cells?
a. Cell work → ATP→ Glucose
b. Glucose → cell work
c. ATP → Glucose
d. Glucose → ATP → cell work
2. Photosynthesis and cellular respiration are two major processes of carbon cycling in living organisms.
Which statement correctly describes one similarity between photosynthesis and cellular respiration?
a. Both occur in animal and plant cells.
b. Both include reactions that transform energy.
c. Both convert light energy into chemical energy.
d. Both synthesize organic molecules as food for the cell.
Use the diagram to answer the following questions as
thoroughly as possible. In the diagram, molecules A
and B represent the products of photosynthesis and
molecules C and D represent the products of cellular
respiration.
3. Explain how photosynthesis and respiration allows for
carbon atoms to be cycled between plants and animals.
4. Describe how energy is transformed as it flows throughout the diagram.
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Biology Keystone Exam Preparation
Name:
Photosynthesis and Cellular Respiration
Date:
Period:
1. A biological process that occurs in plants is represented below.
Which row in the chart below identifies the lettered substances in the process?
A. Row 1
B. Row 2
C. Row 3
D. Row 4
2. Chlorophyll is a molecule shared by prokaryotes and eukaryotes in the process of
A. Cellular respiration
C. Protein synthesis
B. Photosynthesis
D. Polymerization
3. Which of the following best describes the flow of energy in cells?
A. Cell work → ATP→ Glucose
C. ATP → Glucose
B. Glucose → cell work
D. Glucose → ATP → cell work
4. The synthesis of carbohydrates occurs in the stroma of chloroplasts. This process uses energy supplied by
A. ATP
B. CO2
C. PGAL
D. O2
5. Which phrase, if placed in box X, would correctly complete the flowchart shown below?
A. Increased use of starch in root cells
B. Increased concentration of glucose in leaf cells
C. Decreased ATP in root cells
D. Decreased concentration of oxygen in leaf cells
6. Photosynthesis and cellular respiration are two major processes of carbon cycling in living organisms.
Which statement correctly describes one similarity between photosynthesis and cellular respiration?
A. Both occur in animal and plant cells.
B. Both include reactions that transform energy.
C. Both convert light energy into chemical energy.
D. Both synthesize organic molecules as end products
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7. A biological process that occurs in both plants and animals is shown below.
Which row in the chart below identifies the lettered substances in this process?
A. Row 1
B. Row 2
C. Row 3
D. Row 4
8. Complete the table comparing the processes of aerobic and anaerobic respiration.
Process
Location
Reactants
Products
Anaerobic/
Aerobic/Both
Glycolysis
Lactic Acid
Fermentation
Alcoholic
Fermentation
Kreb’s Cycle
Electron Transport
Chain
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Using the following list of words, fill in the blanks with the correct term. Some terms may be used more than once.
ADP
ATP
ATP synthase
carbon dioxide
chemiosmosis
cytoplasm
diffuse
electron transport chain
electrons
FADH2
glucose
glycolysis
greater
intermembrane space
Krebs Cycle
matrix
matrix of mitochondria
NADH/H+
oxygen
phosphate
proton (H+)
pyruvate
water
Aerobic cellular respiration is composed of three steps. The steps in order are
and
,
. During
of the potential energy of a primary food source, e.g. the sugar
, some
, is released during a series of chemical
reactions that occur in the
of the cell.
converted to two molecules of
, a three-carbon molecule. In addition, a small amount of the
total energy in glucose is stored in a few molecules of
electron carriers
, a six-carbon sugar molecule, is
, the energy carrier of the cell, and some high energy
. Glycolysis does not require
the gas
and does not generate
.
, the end product of glycolysis is converted to acetyl CoA, with the release of one
molecules of carbon dioxide, for further processing by the
that occurs in the
. In the Krebs cycle, some high energy electron carriers
and
, and
energy carrier, are generated. Two
molecules are
released for each cycle of the Krebs cycle.
Glycolysis and the Krebs cycle generate only a small amount of
- only 4 molecules per molecule of
glucose. A large amount of the chemical energy from glucose is stored in the form of the electron carriers NADH/H +
generated during
and
the
and FADH2 generated ONLY during
.
converts the energy stored in NADH/H+ and FADH2
The
into potential energy in the form of a
. The electron transport chain is a series of proteins
located in the
. The proteins act as
and some of them are
. The first protein of the electron transport chain accepts
from
regenerating NAD+ that returns to the function in either glycolysis or the
Krebs cycle. Electrons are then transferred sequentially down the
which combines with hydrogen ions (H+) to form
. The final electron acceptor is
. The energy released as the electrons move through certain electron carriers is used to pump
from the
of the mitochondria into the
of mitochondria. This results in the
that serves as a potential energy source.
The concentration of protons is
in the inter membrane space than in the matrix of the
mitochondria. The protons cannot freely
across the inner membrane of the mitochondria. Protons
move across the inner membrane via a large protein called
released by the movement of
group to
to create
. The energy
through the protein is used to add a
. This process is called
.
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